1. Field of the Invention
This invention relates to a seat belt apparatus for use in a vehicle, such as an automobile, and, in particular, to a three-point seat belt apparatus which can be operated by a passenger seated in a vehicle on his or her own will and without taking an awkward or uncomfortable posture.
2. Description of the Prior Art
A three-point seat belt apparatus is well known in the art and is widely used in various vehicles. In the case of a front seat of a passenger car, in particular a two-door car, provided with a seat belt apparatus for each seat, its webbing is normally located in the rear of the front seat and it normally extends along a center pillar of the car when not in use. Thus, after taking the front seat, when a passenger wishes to operate the seat belt apparatus, the passenger must twist his body to grab the webbing and pull it around his body so as to have its lock tongue inserted into a buckle. In such a case, the passenger must take an uncomfortable posture when trying to grab the webbing of the seat belt apparatus, and, thus, there has been a problem of poor operability in such prior art seat belt apparatus.
Various approaches have been proposed so as to improve the operability of a seat belt apparatus, and such approaches include those which utilize the opening and closing motion of a door or the tilting motion of a tiltable backrest of a seat so as to operate the seat belt apparatus, and those which utilize the seating motion of a passenger to activate a driving source for causing the webbing to move to a position easily accessible to the passenger when seated. At the first glance, such an idea of moving the webbing automatically in response to the seating and unseating movement of the passenger appears to be convenient, but, in reality, it is often observed that the seating or unseating movement is not always smooth as desired, for example, depending on various conditions, such as age and physical structure, of the passenger. Thus, the utilization of movement of the passenger for activation of the seat belt apparatus can be detrimental to the intended operability in many cases. Besides, the prior art apparatus is often relatively complicated in structure, which can be a cause of difficulty in manufacture and of malfunctioning.